A modern single crystal X-ray diffractometer and associated crystallographic computing equipment are requested to facilitate four N.I.H. supported research projects at Rutgers. Upgrading of our existing antiquated diffractometer facility will enhance the productivity and quality of the major users' research programs by providing routine crystal structure information. Such information is of vital importance to these projects which involve (a) defining and developing as a spectroscopic probe the ligand to metal charge-transfer spectra of biologically relevant Cu(II)-bonding involving ligation such as imidazole and thiolate (b) developing improved chelation therapy for reducing tissue levels of heavy metal ions such as Cu(II), Cd(II), and Zn(II) (c) structural and synthetic studies of five- and six-coordinate organophosphorus compounds (d) preparation and characterization of cyclic hexapeptide-metal ion complexes which model active sites of non-heme metalloproteins and (e) syntheses of aminocyclitol antibiotics. Health-relatedness derives from the important biological roles of copper proteins and the need for improved chelation therapies for inherited and/or environmentally induced heavy metal overloads, the importance of phosphate intermediates in polymetallic enzyme systems, and the possibilities of preparing synthetic aminocyclitol derivatives which are chemically useful antibiotics.